The draining of fluids from body cavities, hollow organs, cysts or tumour constitutes a serious problem in unborn foetuses or in adults. An example of such a symptom in hollow organs is obstructive uropathies which result in urinary stasis owing to an outflow obstruction in the discharging urinary tracts. Prenatal infravesical foetal obstruction represents a very frequent symptom of obstructive uropathy in foetuses. In some cases, a terminal insufficiency or a pulmonary hypoplasia in the case of anhydramnia develops as a consequence of an infravesical obstruction in new-born babies, as well as subsequently in girls and boys. Many children born with such a defect become dialysis-dependent and in the long term exhibit renal insufficiency. In the worst case, an infravesical foetal obstruction leads to the death of the child.
The cause of an infravesical obstruction is often excessively high pressure in the sphincter region or urethral flap, whereby the urine is only evacuated when the bladder is overfilled, i.e. when the pressure in the bladder is higher than the outlet resistance of the sphincter. This phenomenon is also termed bladder overflow.
Only in rare cases, is the spiral-shaped “Michael Harrison” catheter used in the event of a prenatal infravesical obstruction, which is known for this purpose. The positioning of the Harrison catheter in the urinary bladder of the foetus is extremely complicated and owing to the extremely thick guide needle there is a high risk of premature rupture of the bladder and the triggering of a miscarriage or injury to the patient or foetus. Moreover, the problem arises that the foetus removes the catheter in the womb owing to its play instinct so that a complicated reimplantation of the catheter is necessary. This is the case in particular with the hitherto used but non-fixed pigtail catheter. The latter is not secured in the urinary bladder of the foetus and is often removed by the baby. A reimplantation of the catheter is thereby necessary, which constitutes another surgical intervention for the patient and thus the risk of a miscarriage. In many cases, the symptom remains untreated and, unfortunately, does not lead to the desired treatment result. Upon application of the Harrison catheter, the urinary bladder is permanently evacuated, which leads to bladder hypoplasia. This is unsatisfactory.
The fixing of a catheter via a balloon in the urinary bladder through the urethra is known per se (Foley catheter). Foley catheters have an elastic, inflatable balloon which surrounds the stem of the catheter near to its front end. In the non-inflated state, the balloon is closely adjacent the stem so that it impedes only to a very small extent the insertion of the stem through urethra until an outlet opening at the front end of the stem reaches the desired length, e.g. in the bladder. After the catheter has been brought into the correct position in this way, the balloon is inflated with a fluid medium via a special inflation duct passing through the stem. In the inflated state of the balloon, the inflation conduit is closed so as to prevent removal of the catheter. The catheter remains in the urinary bladder for several weeks. Since the urinary bladder of a foetus in the womb of a expectant mother is not at all accessible or only with difficulty, the application of a Foley catheter, as disclosed in DE 27 52 702 A, is entirely unsuitable for the treatment of a prenatal infravesical foetal obstruction.
DE 32 14 905 A1 discloses a catheter for suprapubic application, which is provided with a puncture needle and a catheter tube receiving the puncture needle in its lumen. The catheter has a stabiliser, which arranged for fastening to the patient's body, with a plate which extends on two opposite sides of the catheter tube and which is slidably mounted by means of an opening on the catheter tube, whereby the stabiliser can be locked by an associated locking device at a respective desired location on the catheter tube. Owing to its construction, this catheter would also be unsuitable for the treatment of a prenatal infravesical foetal obstruction.
Hitherto, the occurrence of renal insufficiency and the other above-mentioned risks have been taken into consideration in the event of an infravesical obstruction, because the danger of infection, premature birth or miscarriage would be too great with the use of the Harrison catheter.